feat(p7): FakeInference deterministic provider + golden eval registry

Task 7.2: FakeInference implements the InferencePort with keyword vocabulary
mirroring the P6 RuleEngine; deterministic (no clock/random) so AI artifacts are
replayable. Golden fixtures (AI_GOLDEN) + inference.spec.ts assert byte-identical
replay, abstention, and Scenario-7 (EVENT never exceeds DISCUSSION certainty).
Controls: abstain()/deny()/setCost().

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-testkit/src/index.ts

@@ -2,3 +2,4 @@ export * from './fakes';
 export * from './replay';
 export { portalMessageBasic } from './fixtures/portal-message-basic';
 export { emailFromUnknown } from './fixtures/email-from-unknown';
+export { AI_GOLDEN, type AiGoldenCase } from './fixtures/ai-golden';